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Detection of Antibodies and Soluble Antigen-Antibody Complexes by Precipitation with Polyethylene Glycol
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1973
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Immunocytochemical TechniqueEngineeringImmunologyFree AntigenImmunotherapyImmunoassaysPolyethylene GlycolBioanalysisSerologic TestingFree AntibodyImmunochemistryAnalytical ChemistryAntibody EngineeringAutoantibodiesClinical ChemistryChromatographyAutoimmune DiseaseAllergyHuman Leukocyte AntigenAutoimmunityHumoral ImmunityAntibody ScreeningBiomolecular EngineeringImmunoglobulin EMedicineAbstract Polyethylene GlycolSoluble Antigen-antibody Complexes
The study modifies the Farr antigen binding test by using polyethylene glycol to separate free antigen from antibody‑bound antigen. PEG at 20% precipitates immunoglobulins, while lower concentrations precipitate soluble antigen‑antibody complexes that remain soluble at higher concentrations, allowing detection of larger antigens such as IgG or thyroglobulin. Immunoglobulins precipitate at 20% PEG, whereas small antigens like bovine serum albumin or insulin stay soluble unless bound to antibodies, in which case they also precipitate at that concentration.
Abstract Polyethylene glycol (PEG) was used in a modification of the Farr antigen binding test in order to separate free antigen from antibody-bound antigen. Most of the immunoglobulins are precipitated at 20% PEG while smaller antigens like bovine serum albumin or insulin are quite soluble at this concentration of PEG. Such antigens are therefore precipitated in 20% PEG if they are bound to antibodies. Furthermore, PEG has been used at lower concentrations in order to precipitate soluble antigen-antibody complexes in conditions at which free antigen or free antibody would be soluble. This second method could be applied to larger antigens such as IgG or thyroglobulin.